Every time when the Bacnet device sends a Simple ACK as answer, bacnet4j throws a "Timeout-Exception" in ServiceFutureImpl
We use the neweset branch bacnet4j 3.2.4 for our software...

two examples with Simple ACK:

    1. Receiving Ack for AcknowledgeAlarm using AcknowledgeAlarmRequest:

a source:
AcknowledgeAlarmRequest req = new AcknowledgeAlarmRequest(
new UnsignedInteger(
localDevice.getConfiguration().getId().getInstanceNumber()),
oId, EventState.lifeSafetyAlarm, timeStamp, new CharacterString("Cobra"), now);

b exception:
com.serotonin.bacnet4j.exception.BACnetException: Timeout waiting for response.
at com.serotonin.bacnet4j.transport.ServiceFutureImpl.get(ServiceFutureImpl.java:71)

c wireshark:
0_1469535392299_1.jpg
0_1469535439741_2.jpg
Simple ACK:
0_1469535477399_3.jpg

    1. addListElement

a source:
RequestUtils.addListElement(localDevice, remoteDevice,
new ObjectIdentifier(ObjectType.notificationClass,
ncNumber),
PropertyIdentifier.recipientList,
new SequenceOf<Destination>(specs));

b exception:
com.serotonin.bacnet4j.exception.BACnetException: Timeout waiting for response.
at com.serotonin.bacnet4j.transport.ServiceFutureImpl.get(ServiceFutureImpl.java:71)
at com.serotonin.bacnet4j.util.RequestUtils.addListElement(RequestUtils.java:526)

c wireshark:

0_1469535599773_B1.jpg

0_1469535610965_B2.jpg
Simple Ack:
0_1469535623935_B3.jpg

Thank you all...